314 THE MYOLOGY OF THE RAVEN. 



the post-pubis beyond it, all of wliicli is beneath the 

 origin of the transversus perinei. The fibres converge 

 as they pass backwards and inwards, and turn in such 

 a way as to permit the muscle to become attached to 

 the quill-butts of the three or four outer rectrices. 



This muscle must be cut across, and its extremities 

 reflected, before we can thoroughly examine the next 

 one. 



153. The depressoi' coccygis arises from rather more 

 than the lower half of the posterior margin of the ischium, 

 as well as from the anterior three-fourths of the posterior 

 margin of the post-pubic element of the pelvis imme- 

 diately beyond it. This line of origin lies well within 

 the marginal border of the bones mentioned, as the pre- 

 ceding muscle is more properly attached to their free 

 edges. 



Its fibres converge as they pass backwards and 

 inwards, and are inserted, somewhat tendinous, to the 

 thickened rim of the inferior and expanded portion 

 of the pygostyle, on the side corresponding with 

 the origin of the muscle. 



154. The lateralis caudcB is composed of usually four 

 fasciculi, more or less joined together by their inter- 

 muscular fasciae, the external fasciculus being by far 

 the most distinct one. This arises from the tip of the 

 transverse process of the first free caudal vertebra at 

 the anterior end of the series, and is inserted on the 

 outer side of the proximal extremity of the external 

 rectrix of the tail. The succeeding fasciculi of the 

 lateralis caudcB arise, in order, from the tips of the 

 next three transverse processes of the caudal vertebrae 

 following the one just alluded to. Their fibres pass 

 backwards, and are inserted on the under side of the 

 quill-butts of the first two or three outer rectrices. 



